Blast actuated closure valve and particulate filter



Dec. 28, 1965 J. J. BAYLES ETAL. 3,225,526

BLAST ACTUATED CLOSURE VALVE AND PARTICULATE FILTER Filed March 5, 1963 2 Sheets-Sheet 1 Dec. 28, 1965 J. J. BAYLES ETAL 3,225,526

BLAST ACTUATED CLOSURE VALVE AND PARTICULATE FILTER Filed March 5, 1963 2 Sheets-Sheet 2 IIIA-10Q; 4er/.14.211.125

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INVENTORS United States Patent O 3,225,526 BLAST ACTUA'FED CLSURE VALVE AND PAR'IICULATE FILTER John .1. Bayles, 1560 Ieal Club Road, and Arthur A. Denny, 3440 S. J St., both of Gxnard, Calif. Filed Mar. 5, 1963, Ser. No. 263,085 7 Claims. (Cl. 55--420) (Granted under Title 35, U.. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally to the ventilation of underground personnel shelters for use in the vicinity of possible nuclear bomb attacks and specifically to a ventilating closure which may be actuated by the bomb blast itself.

One of the most important considerations in the design of underground shelters for use in the protection of personnel from nuclear attacks is adequate ventilation. Normally, such ventilation may be provided by one or more ventilation pipes or ducts leading from the shelter to the surface of the ground above. In the event of the explosion of an atomic bomb or other nuclear device within effective range of the shelters, some provision must be made to immediately seal-off the ventilation duct leading to such shelter. Conversely, when the worst effects of the bomb have passed on over, the sealing-off or closure device should automatically open the ventilation duct for its intended purpose.

Gther types of blast valves have been previously developed for such purposes. Such valves, however, have usually been connected with the upper exposed end of the ventilation duct and have thus been subject to initial blast damage. Also, such blast valves have generally been secondarily actuated by mechanical or electrical means triggered by a primary means operable as a function of the pressure of the blast wave or as a function of the intense light produced by the initial explosion. Such methods have been found too complex with decreased reliability in proportion to increased complexity. Furthermore, such prior valves have been one-shot devices. After each blast, they required re-cocking, recharging (in the case of valves operated by small explosive charges), re-opening, or otherwise the attention of trained personnel with the additional hazard of the exposing of such personnel to radioactive fallout.

Another disadvantage found in previous blast valve arrangements has been that no provision has been made to filter the incoming air. In some types of ventilation equipment for underground shelter use, it has been proposed to utilize sand or earth. Obviously, such types of filter are not only inadequate for such use but are possibly unsanitary due to decaying vegetable material contained therewith and deleterious to health by allowing the finer particles to be drawn into the shelter. This latter condition is particularly possible where forced suction ventilation is used and the filtering material has been allowed to become thoroughly dry.

The principal object of our invention, therefore, is to provide a blast actuated Ventilator valve and particulate filter that is simply constructed and positively operated by the blast wave from the explosion of a nuclear device.

Another object of our invention is to provide a blast actuated closure for a ventilator duct which is continuously repeatable in action without the necessity of recharging or recocking or other mechanical or electrical manipulation after each blast.

A further object of our invention is to provide a blast actuated ventilator valve which establishes a positive seal in a ventilation duct for protective shelters and is 3,225,526 Patented Dec. 28, 1965 capable of continuous, automatic action in preventing the ingress of blast waves regardless of duration and frequency.

A still further object of our invention is to primarily provide a low cost and practically maintenance free means of preventing air pressure build-up in an air raid shelter due to overpressures from atomic blasts and secondarily to provide particulate infiltration of the incoming air with its possible radioactive fallout content.

Other objects and advantages of this invention will be appreciated in conjunction with the following detailed description and accompanying drawings wherein:

FIGURE l is an elevation of the device, partly brokeny away to show certain parts in cross-section;

FIGURE 2 is enlarged partial view showing details of construction of the part shown in FIG. l;

FIG. 3 is an elevation, similar to FIG. 1, showing a modification of the invention;

FIG. 4 is an enlarged partial view based on FIG. 3;

FIG. 5 is an elevation, similar to FIG. 1, showing another modification of the invention;

FIG. 6 is an enlarged partial view based on FIG. 5;

FIG. 7 is an elevation, similar to FIG. 1, showing still another modification of the invention; and

FIG. 8 is an enlarged partial view based on FIG. 7.

With reference to FIGS. 1 and 2, the invention comprises a ventilation duct 10 which leads from the surface of any desired type of underground protective shelter. As shown, this duct consists of two duct sections 11 and 12 having foundation rings 13 secured to the mating ends of the duct sections by welding, brazing, or other attachment means. These rings are provided with mating bolt holes for the reception of fastening bolts 14 and 15. These duct sections are formed from fairly substantial sheet metal and may be circular, square, or rectangular in cross section.

Suspended internally of the mating joint or end of duct section 11 and adjacent thereto is found a perforated metallic plate 16 having perforations 17. A similar plate 1S with perforations 19 is secured to the corresponding joining end of duct section 12. These plates may be welded, brazed, or otherwise suitably secured to the inner walls of their duct sections. While not absolutely necessary for e'icient operation, the perforations 17 and 19 are generally matched in substantial alignment.

Intermediate of the two fixed plates 16 and 18, a movable plate 2f) having perforations `21 is resiliently suspended. In this embodiment, the resilient means consists of a plurality of compression springs 22 mounted around the periphery of the supporting plates in recessed sockets 23. This plate 20 is of a size which will just fit comfortably inside the joint of the two duct sections and, of course, corresponds to the configuration thereof. The perforations 21 are smaller, preferably, than perforations 17 and 19 in the fixed plates 16 and 1S and are symmetrically offset therefrom.

Thus, as the blast from the nuclear explosion moves downwardly through duct section 11, plate 2t) is forced downwardly against the compression of the lower set of springs 22 on to the upper surface of lower plate 1S. Due to the offset relationship of the perforations 17 and l21, the passageway is efectually sealed against the further passage of pressurized air and any particulate matter borne thereby. As the pressure wave decreases, movable plate 26 will be-forced upwardly to its neutral position Iby the lower set of springs 22. In the event a negative pressure wave then ensues, the atmospheric vacuum then induced will `tend to release the pressure from the underground shelter. This etiiux will then be controlled by a corresponding upward movement of movable plate 20 against the upper set of springs 22 until the plate 20 abuts against the lower surface of plate 16. In the event the shelter is crowded with personnel, as would likely be the case, such negative pressure control would be highly important for the health and well-being of the sheltered personnel.

The embodiment of our invention depicted in FIGS. 3 and 4 is similar to that previously shown and described in connection with FIGS. l and 2 with the exception that the springs 22 have been replaced with resilient pads 24 and 25. These .resilient pads could be formed from an fopen-celled, foamlike material such as foam rubber, polyurethane, or other similar resilient and foraminous material. Whe-re the underground shelters are erected in desert or beach areas, the use of such foam-like materials might be particularly advantage-ous as possessing, inherently, a greater filtering effect. While the offsetting of the perforations in the various plates ris also employed, in this modification, the blast valve effect is principally accomplished by the compression of the foam-like material, thus effectually closing the foramina present therein.

The modification shown in FIGS. and 6 consists of a different mode of employment of the perforated bafiie plates. Here retainer rings 26 and 27 are secured internally of the duct sections 11 and 12, adjacent their mating edges, by welding, brazing, or other suitable means. These rings conform to the internal configuration of the duct. Floating or movable perforated plates 28 and 29 are separated by a resilient pad 30 of polyurethane, foam rubber or other similar foam-like, foraminous material and are normally forced upwardly and downwardly against their associated retainer rings. Thus, when the pressure wave from the atomic blast is descending down the duct, plate 28 is forced downwardly compressing the pad against the lower plate 29 and initiating the blast valve action by closing the pores or foramina of the resilient pad 30. As the effect of the blast pressure wave dimnishes, the resilient pad extends upwardly, returning the plate 28 to its normal position under and against the retainer ring 26. The extension of the pad re-opens its pores and allows it to pass air in its normal fashion. In the event of an atmospheric negative pressure wave, the action of the plates is reversed from that described above.

The modified form of the invention illustrated in FIGS. 7 and 8 is very similar to that shown in FIGS. 5 and 6. In this embodiment, the retainer rings 26 and 27, shown in FIGS. 5 and 6, have been replaced with discs or plates of perforated, expanded metal, 31 and 32. As heretofore, these discs or plates conform to the general configuration of the duct and are secured in place by welding, brazing, or other suitable means. Such plates of expanded metal might be found very useful and important in areas where sizable rocks or other material, heavier than the usual dust present in such explosions on land, might be carried by the pressurized air wave.

Otherwise the operation of the device remains as described above in connection with FIGS. 5 and 6.

While various embodiments of our invention have been shown and described, it should be appreciated that, while all depend on the principle of a moving plate operated by blast pressure Waves in either direction, the various modifications have been suggested as being alternative modes of construction available in the field. Many other modifications are, of course, possible but it is believed that any such further modification employing the principle set forth above would not only be covered by the spirit of our invention but would fall within the scope of the appended claims wherein we claim:

1. A blast actuated closure valve and particulate filter in the ventilation duct of an underground protective shelter comprising, in combination:

a ventilation duct leading from an underground shelter to the earth surface above said shelter;

a plurality of parallel plates having non-aligned perforations installed in a spaced relationship across the cross-sectional area of said duct with at least one of the plates being movable substantially into abutting relation to an adjacent plate along the longitudinal axis of said duct in response to a pressure wave progressing through a portion of said duct;

resilient means for maintaining the normal separation of said plates from each other;

2. A blast actuated closure valve and particulate filter in the ventilation duct of an underground protective shelter comprising, in combination:

a ventilation duct leading from an underground shelter to the surface -of the earth above said shelter;

a series of three perforated plates installed in a spaced relationship across the cross-sectional area of said duct, the first and third of said plates being fixedly positioned in said duct and the second perforated plate being floatingly positioned intermediate of said first and third plates so as to be movable along the longitudinal axis of said duct in response to a pressure wave progressing through a portion of said duct;

resilient means positioned between said plates for positioning said fioating second plate substantially equidistant from said first and third plates;

3. A blast actuated closure valve and particulate filter as claimed in claim 2 wherein the perforations in said fixed first and third plates are of a similar number and size and in substantial alignment with each other while the perforations in said fioating second plate are misaligned with respect to the perforations in said first and third plates whereby as said floating second plate is forced by said pressure wave in juxtaposition with either one of said fixed plates the passageway through said duct is substantially closed.

4. A blast actuated closure valve and particulate filter in the ventilation duct of an underground protective shelter comprising, in combination:

a ventilation duct leading from an underground shelter to the surface of the earth above said shelter;

three perforated plates installed in a spaced relationship across the cross-sectional area of said duct intermediate of the ends thereof, the first and third said plates being fixedly secured in said duct and the second perforated plate being fioatingly positioned intermediate of said first and third plates so as to be movable along the longitudinal axis of said duct in response to a pressure wave progressing through a portion of said duct;

the perforations of said second plate being misaligned with respect to the perforations in said first and third plates; and

a pair of resilient and foraminous pads sandwiched between said perforated plates whereby said second floating plate is resiliently supported substantially centrally between said first and third plates.

5. A blast actuated closure valve and particulate filter in the ventilation duct of an underground protective shelter comprising, in combination:

a ventilation duct leading from an underground shelter to the surface of the earth above said shelter;

a pair of perforated plates installed in a spaced relationship across the cross-sectional area of said duct intermediate of the ends thereof with each plate being movable along the longitudinal axis of said duct in response to a pressure wave progressing through a portion of said duct;

a pair of retainer rings secured to the inner wall of said duct for limiting the movement of said plates with respect to each other and that section of the duct in which the movable plates are installed; and

a resilient and foraminous pad sandwiched between said pair of movable plates for maintaining the separation between said plates and for acting as a valve to control the passage of the pressure Wave and a filter to filter out any particulate matter carried by said pressure wave when the pad is compressed between said plates by the pressure wave.

6. A blast actuated closure valve and particulate lter in the ventilation duct of an underground protective shelter comprising, in combination:

a ventilation duct leading from an undergroud shelter to the surface of the earth above said shelter;

a pair of perforated plates positioned in a spaced relationship across the cross-sectional area of said duct intermediate of the ends thereof with each plate being movable along the longitudinal axis of said duct in response to a pressure wave progressing through a portion of said duct;

means associated with said movable plates for retaining said plates in said duct and for limiting the movement of said plates with respect to each other and to that section of the duct in which they are installed; and

a pad of resilient and foraminous material positioned between said movable plates, said pad conforming closely to the configuration of said plates and serving to resiliently space said plates from each other and to maintain said plates in normal juxtaposition with said retaining means as well as acting as a valve to control the passage of the pressure wave and a filter to filter out any particulate matter carried by said pressure wave when the pad is compressed between said plates by the pressure wave.

7. A blast actuated closure valve and particulate lter in the ventilation duct of an underground protective shelter as claimed in claim 6 further characterized by said retaining means comprising sections of expanded metal iixedly secured to the inner walls of said duct and mounted outwardly of said movable perforated plates.

References Cited by the Examiner FOREIGN PATENTS 220,961 4/ 1959 Australia. 396,360 10/1931 Great Britain. 210,059 9/ 1940 Switzerland.

HARRY B. THORNTON, Primary Examiner, 

1. A BLAST ACTUATED CLOSURE VALVE AND PARTICULATE FILTER IN THE VENTILATION DUCT OF AN UNDERGROUND PROTECTIVE SHELTER COMPRISING, IN COMBINATION: A VENTILATION DUCT LEADING FROM AN UNDERGROUND SHELTER TO THE EARTH SURFACE ABOVE SAID SHELTER; A PLURALITY OF PARALLEL PLATES HAVING NON-ALIGNED PERFORATIONS INSTALLED IN A SPACED RELATIONSHIP ACROSS THE CROSS-SECTIONAL AREA OF SAID DUCT WITH AT LEAST ONE OF THE PLATES BEING MOVABLE SUBSTANTIALLY INTO ABUTTING RELATION TO AN ADJACENT PLATE ALONG THE LONGITUDINAL AXIS OF SAID DUCT IN RESPONSE TO A PRESSURE WAVE PROGRESSING THROUGH A PORTION OF SAID DUCT; RESILIENT MEANS FOR MAINTAINING THE NORMAL SEPARATION OF SAID PLATES FROM EACH OTHER. 